This application claims priority from European Patent application No. 05 028 124.5 filed Dec. 22, 2005, incorporated herein by reference in its entirety.
The invention relates to a sputter apparatus with a pipe cathode and to methods of operating the apparatus.
Applying layers onto substrates frequently takes place by means of a sputter process. In this sputter process substrates, for example glass or synthetic films, are introduced into a vacuum chamber in which a plasma is located.
The positive ions of the plasma are therein transported onto a target which is located at a cathode. These positive ions strike particles out of the target and these particles are transported toward the substrate to be coated and are deposited there.
In the proximity of the target permanent magnets are frequently disposed in order to increase the number of ions in the plasma whereby even more particles can be struck out of the target. Such a combination of permanent magnets and cathode is referred to as a magnetron.
In principle, one differentiates herein between planar and round or tubular magnetrons.
In the case of the tubular magnetrons a tubular target is placed onto the outside of a cylindrical cathode. This overall configuration can rotate about the longitudinal axis of the cathode. Since in these tubular magnetrons the yield of the target material is higher than in planar magnetrons, these tubular magnetrons are increasingly gaining in importance.
For example a cylindrical magnetron is known which is located in a vacuum chamber (EP 0 500 774 B1). The target structure herein rotates about its longitudinal axis while the magnets are stationary.
Furthermore is known a magnetron cathode rotating about the longitudinal axis comprising such a magnet configuration, such that two different opposing substrates are coated simultaneously (DE 41 26 236 A1).
A rotary cathode with at least one target disposed thereon is also described (EP 0 703 599). Instead of rotating about its own axis, the rotary cathode carries out an oscillating rotary movement, wherein the angle of oscillation is up to 90°. This is intended to solve the task of being able to change the target material rapidly and without opening the vacuum installation.
U.S. published patent application 2004/0149576 A1 discloses a sputter apparatus which includes a rotatable receptor, in which is located a coaxial cooling tube. An energy supply cable is here connected to a sputter magnetron.
Furthermore is known a rotatable and tubular hollow cathode in which an AC current supply line is connected to the hollow cathode (U.S. Pat. No. 5,814,195).
Lastly, a pipe cathode is also known which comprises a rotatable leadthrough for a water supply, at whose atmospheric side, fixed receptor water hoses are attached (M. Wright et al., “Design advances and applications of the rotatable cylindrical magnetron”, Journal of Vacuum Science and Technology, Part A, AVS/AIP, Melville, N.Y., US, Vol. 4, No. 3, 1986, pp. 388-392, XP002314779, ISSN 0734-2101).
The task of the invention is to provide a sputter apparatus with a pipe cathode in which the supply of the pipe cathode takes place via flexible conducting line elements.
This task is solved according to the present invention.
The invention thus relates to a sputter apparatus with a pipe cathode and a method for operating this sputter apparatus. The supply of current, cooling fluid and other media to the pipe cathode herein takes place via flexible lines or tubing which can be wound about a receptor. When the pipe cathode executes a pendulum movement, the lines and/or tubes are wound onto the receptor or unwound from it. The pendulum movement of the pipe cathode is therein preferably such that the pipe cathode is rotated by a specific first angle in a first direction and subsequently by a specific second angle in a second direction, the second angle being different from the first angle.
The advantage attained with the invention comprises in particular that the supply with cooling fluid and/or current can take place through flexible lines or hoses. Therewith disposing a rotating seal, for example at the water leadthrough can be omitted since it is no longer necessary to transfer the cooling medium from a static to a rotating part. The water hose is disposed directly on the rotating pipe cathode.
Moreover, the technically highly complex rotary leadthroughs require much space, such that the solution according to the invention is additionally space-saving.
It is also of advantage in the invention that it becomes possible to supply the pipe cathode, for example via a cable, with current, wherewith the technically complex function components of a sliding contact can be omitted and, consequently, the current is not limited. The sputter power can therewith be increased. Of disadvantage in the conventional sliding contacting is the generation of particles. In the case of contacting in vacuum these particles can become deposited on the substrates to be coated, which leads to the formation of pin holes in the coating. If the sliding contacts, and therewith the power supply lines, are disposed at the atmospheric pressure side, the metallic structural parts of bearing and rotary leadthrough can be damaged through eddy currents when using AC current.
A further advantage of the invention comprises that flexible measuring or signal lines can also be connected with the pipe cathode. For example, it becomes hereby possible to determine the target temperature. If the target temperature is on the verge of reaching a critical value or of exceeding it, the cooling means supply can be increased via a control line.
Disposing the flexible supply elements takes place in such manner that the pipe cathode, as is the case in the conventional sputter processes, can continue to be rotated by at least 360° about its own longitudinal axis. The rotation takes therein place in the form of a discontinuous circular movement, whereby a uniform erosion of the target material, and therewith a uniform coating of the substrate, continues to be given.
One advantage of the invention further also lies therein that the maintenance of the coating installation is facilitated, since the technically complex and complicated fixtures of rotary water leadthroughs and the sliding contacts are no longer present.
Lastly, the invention is also less prone to wear and tear.
An embodiment example of the invention is depicted in the drawings and will be described in further detail in the following. In the drawing show: